At a briefing for political journalists yesterday, a No 10 spokeswoman confirmed that Mr Blunkett still had the Prime Minister's support.

In his weekend statement, Mr Blunkett, 57, who is on holiday with his three sons from his former marriage, said: "After my divorce I decided not to talk again about my subsequent private life.

Discreet meetings

"I have stuck to that principle over the years, whatever the pressure to confirm or deny a particular story, and defended all politicians' right to a degree of privacy in their private life.

"I am adhering to this approach now. My personal life is my business and has never compromised my jobs as an MP and Cabinet minister.

"Anyone purporting to speak about my private life does so without my knowledge or authority."

According to reports, Mr Blunkett and Ms Fortier were introduced in 2001, and have met discreetly in London and enjoyed getaways to the countryside.

A source said to be close to the Home Secretary said : "In truth he has been devastated at being unable to lead a normal life with her. He is a man very deeply in love.

"He has one of the busiest diaries in government, but when time allows there are passionate moments.

'He is totally in love with her'

"None of this rests easily with David. He has a deep conscience. But this is no casual fling. He's totally in love with her. Complete and utter devotion. She is an incredibly bright and vivacious woman.

"They are on the same plane, emotionally and intellectually."

The friend added: "He wants to be with her within the confines of a normal, loving relationship.

"They can't do the things all normal lovers do, like going out for dinner or strolling in the streets. Instead they have to hide themselves away.

"But until now she has refused to leave her husband for him.

"Still, you can't hold a three-year relationship with someone, against all the odds, without having a huge reservoir of love and affection to get you through the difficult times."

Ms Fortier moved to Britain in 1987. She was educated at Vassar University in New York State in the early 1980s. She took a degree in British politics and social history and has worked at a number of magazines including Cosmopolitan.

Spectator editor Boris Johnson, the Conservative MP for Henley, said: "She is a terrific publisher and has my complete support."